Zdenek Dvorak wrote:
Hello,
The attached fixes *that*, but this just causes a crash deeper in trying
to free some chains.
[...]
Sorry for the problems and thanks for looking into them.
Ken, please reread the email. The issue is *not* fixed according to
Daniel, there's still another problem. Could you look into it,
please?
I would like permission to revert zdenek's patch for a few days. There
is nothing wrong with zdenek's patch, pe se, but it excercises a part of
df that should work but does not.
I don't quite like this idea; as you yourself say, the problem is not in
that patch (in fact, mainline bootstraps and passes regtesting with it
without your patch); so I think that if we indeed want to go into
reverting patches, it should be the one causing the problem (and I have
a followup patch that I would like to be able to test).
Btw.: of course it may happen that some patch sometimes breaks
bootstrap, it happened to everyone of us. But, with your patch, not
even libgcc builds. This means that you did not even try to build gcc
before commiting your patch. Please do that next time. In fact,
running at least a partial bootstrap till gengtype is run helped me
avoid introducing bootstrap failures (caused by unexpected interaction
with patches commited since I tested the patch fully the last time)
several times, so it is a good idea even if you are quite sure that no
such problem may occur.
Zdenek,
There are several problems here. If I fix the immediate problem, you
only hit the next one.
The underlying problem is that when you change the blocks in the program
and you have def-use or use-def chains built, these have to be cleaned
out in a way that was not being done.
If I revert my patch, it will fix the immediate problem that
df_set_blocks crashes but will most likely happen in other places. It
is because of the other places that it is not sufficient to just revert
my patch.
Yours is currently the only place that plays with blocks when the
use-def chain problem has been built. This is something that I
advertised could be done and I blew it. But removing my last patch is
not going to fix that, it will still be broken, it will just fail less
often.
Kenny
We could revert my storage patch, but the problem is much deeper than
that. The storage patch only causes this problem to happen when
bootstrapping. The problem will still be there and may cause random
ices when running zdeneks code.
The problem is that when ever you delete any basic blocks, you need to
get rid of the def use and use def chains that either start or end in
the deleted block, furthermore, this has to be done before the
instructions are deleted for those blocks. This will take me a day to
get correct.
Zdenek's patch is the only code that manipulates the blocks after
use-def or def-use chains are built.
This analysis seems wrong to me -- the crash occurs when called from
estimate_probability, and we do not change CFG in branch prediction.
Zdenek
